When patients present with pain, we can usually put each patient in one of two categories: they weren’t doing enough activity, or they were doing too much. Let’s give you two examples. The most obvious is in the springtime, when the weather is nicer, people will take up running; but this is after not running for months because of the season and weather. When the person tries to run the same amount of miles, or as fast as they did prior to their hiatus, is when they get in trouble. This is a simple case of "too much, too soon": the amount of excessive load on the tissues causes strain and will send a signal to the brain for help because something is wrong.